On hydraulic efficiency of pitched blade impellers

This study provides a description of a pitched blade impeller as an axial pump. For the turbulent flow regime of an agitated liquid in a fully baffled cylindrical vessel under a few simplifying assumptions, we formulate the relation among the impeller dimensionless total head, the impeller power number, and the dimensionless impeller pumping capacity (the flow number). The hydraulic efficiency of pitched blade impeller is determined from experimental data found in literature (the flow numbers and the power numbers). It follows from the results of the calculations that the hydraulic efficiency of pitched blade impellers increases significantly with decreasing pitch angle, and also with decreasing impeller vessel diameter ratio.

Research highlights▶ Hydraulic efficiency of pitched blade impellers as a measure of their flow effectiveness. ▶ The system of a pitched blade impeller and a mixing vessel with internals can be considered as a pipeline with an axial pump. ▶ Pitched blade agitators create both axial and radial discharge flow. ▶ The significant influence of the impeller pitch angle on its hydraulic efficiency. ▶ Selecting the optimum size and pitch angle is important for industrial flow-sensitive operations.